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| CHARACTERISTICS OF TRANSIENT MAGNETIC NEARBY FIELD IN PROCESS OF COAL IMPACT DAMAGE |
| LI Chengwu，XIE Beijing，YANG Wei，WEI Shanyang |
| (Faculty of Resources and Safety Engineering，China University of Mining and Technology，Beijing 100083，China) |
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Abstract By a standard split Hopkinson pressure bar(SHPB) dynamic test device and ZDKT–1 type transient magnetic vibration test system，the dynamic properties of coal and the characteristics of the transient magnetic nearby field in the process of coal impact damage are researched under impact velocity of 4.174–17.652 m/s. The one-dimensional stress wave theory and the signal analysis of Hilbert-Huang transform(HHT) method are used to analyze the strain signal and the transient magnetic signal，respectively. The results show that：(1) The dynamic response of coal transforms from hardening to softening within certain range of strain rate；(2) The magnetic field has varied obviously in 4 cm distance of coal sample area during coal dynamic impact process，and it shows that the duration is less than 2 s and the frequency is less than 40 Hz through the ensemble empirical mode decomposition(EEMD) analysis；(3) The characteristics of the signal curve of the transient magnetic changes in coal impact damage process is shown that the first performance straight up，then exponential decline，at the end of small oscillation；(4) The amplitudes of transient magnetic field changes in coal impact damage process rises with the impact velocity，average strain rate，the maximum strain rate and the limit value of fracture stress increasing，while it reduces with the failure strain increasing，but the data are of a larger dispersion.
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Received: 31 October 2011
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| [1] 何学秋，刘明举. 含瓦斯煤岩破坏电磁动力学[M]. 徐州：中国矿业大学出版社，1995：153–168.(HE Xueqiu，LIU Mingju. Electromagnetic dynamics of coal containing gas destruction[M]. Xuzhou：China University of Mining and Technology Press，1995：153–168.(in Chinese))
[2] 何学秋，王恩元，聂百胜，等. 煤岩流变电磁动力学[M]. 北京：科学出版社，2003：102–137.(HE Xueqiu，WANG Enyuan，NIE Baisheng，et al. Electromagnetic dynamics of coal or rock rheology[M]. Beijing：Science Press，2003：102–137.(in Chinese))
[3] 聂百胜，何学秋，王恩元，等. 煤体剪切破坏过程电磁辐射与声发射研究[J]. 中国矿业大学学报，2002，31(2)：609–611.(NIE Baisheng，HE Xueqiu，WANG Enyuan，et al. Study on electromagnetic radiation and acoustic emission in shearing process of coal[J]. Journal of China University of Mining and Technology，2002，31(2)：609–611.(in Chinese))
[4] 王恩元，何学秋. 煤岩变形破裂电磁辐射的实验研究[J]. 地球物理学报，2000，43(1)：131–137.(WANG Enyuan，HE Xueqiu. An experimental study of the electromagnetic emission during the deformation and fracture of coal or rock[J]. Chinese Journal of Geophysics，2000，43(1)：131–137.(in Chinese))
[5] 何学秋，聂百胜，王恩元，等. 矿井煤岩动力灾害电磁辐射预警技术[J]. 煤炭学报，2007，32(1)：56–59.(HE Xueqiu，NIE Baisheng，WANG Enyuan，et al. Electromagnetic emission forecasting technology of coal or rock dynamic disasters in mine[J]. Journal of China Coal Society，2007，32(1)：56–59.(in Chinese))
[6] 撒占友，何学秋，王恩元. 煤与瓦斯突出危险性电磁辐射异常判识方法[J]. 煤炭学报，2008，32(12)：1 373–1 376.(SA Zhanyou，HE Xueqiu，WANG Enyuan. Electromagnetic radiation anomaly identification method of coal and gas outburst fatalness[J]. Journal of China Coal Society，2008，32(12)：1 373–1 376.(in Chinese))
[7] 万国香，李夕兵. 应力波作用下节理面前后电磁辐射强度的变化[J]. 地震学报，2009，31(4)：411–423.(WANG Guoxiang，LI Xibing. Intensity variation of electromagnetic emission of the rock masses with joints under stress wave action[J]. Acta Seismologica Sinica，2009，31(4)：411–423.(in Chinese))
[8] 万国香，李夕兵. 岩石破裂电磁辐射幅值与岩石属性参数的关系[J]. 力学与实践，2008，30(2)：70–73.(WANG Guoxiang，LI Xibing. Relationship between the electromagnetic radiation and rock masses paramenter during rock failure[J]. Mechanics and Practice，2008，30(2)：70–73.(in Chinese))
[9] 万国香. 应力波作用下岩石电磁辐射与声发射特性研究[博士学位论文][D]. 长沙：中南大学，2008：15–67.(WANG Guoxiang. Study on the charateristics of the electromagnetic emission and acoustic emission in rock under stress wave [Ph. D. Thesis][D]. Changsha：Central South University，2008：15–67.(in Chinese))
[10] 李成武，许延超. 煤与瓦斯突出主要影响因素主成分分析[J]. 煤矿安全，2007，38(7)：14–17.(LI Chengwu，XU Yanchao. The component analysis of mainly affecting factors of coal and gas outburst[J]. Coal Mine Safety，2007，38(7)：14–17.(in Chinese))
[11] DAVIES E D H，HUNTER S C. The dynamic compression testing of solids by the method of the split Hopkinson on pressure bar[J]. Journal of the Mechanics and Physics of Solids，1963，11(2)：155–179.
[12] 李胜林，刘殿书，李祥龙，等. ? 75 mm分离式霍普金森压杆试件长度效应的实验研究[J]. 中国矿业大学学报，2010，39(1)：93–97.(LI Shenglin，LIU Dianshu，LI Xianglong，et al. The effect of specimen length in ? 75 mm split Hopkinson pressure bar experiment[J]. Journal of China University of Mining and Technology，2010，39(1)：93–97.(in Chinese))
[13] ZENCKER U，CLOS R. Limiting conditions for compression testing of flat specimens in the Hopkinson pressure bar[J]. Experimental Mechaincs，1998，39(4)：343–348.
[14] WEINONG W，CHEN B S. Split Hopkinson(Kolsky) bar design，testing and applications[M]. [S.l.]：[s.n.]，2011：7–17.
[15] SEMION K，THOMAS P F，HUANG N E，et al. On the Hilbert-Huang transform data processing system development[C]// Proceedings of 2004 IEEE Aeaospace Conference. [S.l.]：[s.n.]，2004：1 961– 1 979.
[16] 李夕兵，凌同华，张义平. 爆破震动信号分析理论与技术[M]. 北京：科学出版社，2009：82–84.(LI Xibing，LING Tonghua，ZHANG Yiping. Analysis of theory and technology signal of blast vibration[M]. Beijing：Science Press，2009：82–84.(in Chinese))
[17] 薛 嫚. 总体平均经验模式分解法的理论研究[硕士学位论文][D]. 哈尔滨：哈尔滨工程大学，2007：28–30.(XUE Man. A study of ensemble empirical mode decomposition[M. S. Thesis][D]. Harbin：Harbin Engineering University，2007：28–30.(in Chinese))
[18] WU Z H，HUANG N E. Ensemble empirical mode decomposition: a noise-assisted data analysis method[J]. World Scientific，2009，1(1)：1–41.
[19] DONNBO D. Denoising by soft-thresholding[C]// Proceedings of the IEEE Transactions on Information Transactions on Signal. [S.l.]：[s.n.]，1996：2 141–2 150.
[20] 李英雷，胡时胜，彭建祥，等. 霍普金森压杆实验中的磁场干扰[J]. 爆炸与冲击，2002，22(3)：274–276.(LI Yinglei，HU Shisheng，PENG Jianxiang，et al. Magnetic influence on strain signal of Hopkinson pressure bar[J]. Explosion and Shock Waves，2002，22(3)：274–276.(in Chinese)) |
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2012, Vol. 31 
